Magnetic devices and electric or magnetic fields have been used in the past for the purpose of providing medical benefits to people. Some of these medical benefits are more direct than others. In some instances, one or more magnets are simply disposed near an area to be treated based on a belief that exposure to a magnetic field would holistically cure human afflictions, ailments, and diseases. Some examples of the placement of magnets near a treated area to bring about holistic therapy include U.S. Pat. Nos. 7,029,432 to Woo, 6,796,973 to Bates, and 6,776,753 to Holcomb. Similarly, U.S. Pat. No. 6,210,317 to Bonlie describes a method of treating a patient who lives in a relatively weak magnetic field by providing a device having high intensity unidirectional magnetic field aligned to pass through the patient's body in a particular manner.
In other therapeutic applications, magnetic devices have been used to help control the position of an implant in a patient's body. U.S. Pat. No. 6,849,076 to Blunn, for example, uses magnets and electric fields to non-invasively apply extending or tensioning forces to a distraction device disposed in bone. Likewise, U.S. Pat. No. 4,024,588 to Janssen describes an artificial joint that uses magnets or magnetizable elements to attract or repel component of the joint, and U.S. Pat. No. 6,387,096 describes the use of an array of magnets to secure and align portions of treated bone.
Magnets also have been used to attract materials to a part of the body. U.S. Pat. No. 6,779,871 to Halpern, for instance describes a method for repairing cartilage by deploying a porous, magnetic scaffold at the damaged site and injecting magnetically tagged growth promoting material near the area of the defect. The magnetically tagged growth promoting material is then drawn into the apertures of the porous scaffold by magnetic attraction.
While these prior uses of magnets and electric or magnetic fields may have had varying degrees of efficacy, none of them provided the ability to dynamically adjust to changing conditions in the treated area. In addition, none of these prior devices and treatment methods provided the capability to be used in treating a joint by causing it to move through at least a portion of its range of motion or through a repeated cycle of relative motion between two elements implanted in the treated area. Furthermore, past uses of magnets in medical therapy have not been utilized to help contain a therapeutic agent to a treated area.